What is the function of "az" in this sentence?
Does it change the meaning when it is after "ezek"?
It's just that you have to say "the buildings", something you wouldn't do in English, that's all. It has no special importance.
ahhh. So to say "these are buildings" you would say "ezek épületek" but to say "these buildings" you would say "ezek az épületek"?
Demonstrative adjectives (this, that, these, those) are formed in the following way in Hungarian: ez az épület = this building; az az épület = that building; ezek az épületek = these buildings; azok az épületek = those buildings.
These are buildings _ Ezek épületek. These are the buildings _ Ezek az épületek.